marcet boiler manual

SOLTEQ® MARCET BOILER (Model: HE169) ________________________________________________________

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1.0 INTRODUCTION

The SOLTEQ® Marcet Boiler (Model: HE169) is a bench top unit designed for the demonstration of the basic principal in Thermodynamics studies which is the boiling phenomenon. Students will be able to study the relationship between the pressure and temperature of saturated steam in equilibrium with water. The saturation pressure curve can be determined at the pressure within 10 bar (150 lb/in2).


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2.0 GENERAL DESCRIPTION The unit consists of a stainless steel pressure vessel fitted with high pressure immersion electrical heater. The unit also comes together with a safety relief valve, temperature and pressure measuring devices. Water feed port is installed to allow water charging. The unit comes with comes with temperature and pressure transducers so that students will be able to read the respective values on the digital indicators easily. The water heater is protected from burnout by setting the maximum operating temperature with a temperature controller.

2.1 Unit Construction

Figure 1: Unit Construction for Marcet Boiler (Model: HE169)

1. Pressure Transducer 6. Bourdon Tube Pressure Gauge

2. Pressure Indicator 7. Temperature Sensor

3. Temperature Controller/Indicator 8. Pressure Relief Valve

4. Control Panel 9. Heater

5. Bench 10. Water Inlet Port & Valve

1

2

3

4

6

7

8

10

9

5


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2.2 Description and Assembly

The SOLTEQ® Marcet Boiler (Model: HE169) consists of mainly the following items: a) Pressure Vessel

Capacity : 3 Liters Material : Stainless Steel 304 Design Pressure : 30 bar Operating Pressure : 10 bar Certification : DOSH certified

b) Pressure Gauge Type : Bourdon Tube Range : 0 – 20 bar (g)

c) Pressure Transducer Wetted Material : Stainless Steel Case Material : Stainless Steel Range : 0 – 16 bar (abs)

d) Electrical Heater Power: 2000W Type: Immersion Type Safety: High temp cut-off by means of a temperature controller

e) Temperature Sensor Type: RTD (Class A) Range: 0 – 200°C

f) Safety Features Pressure Relief Valve (Set at 15 bar), Temperature Controller (Set at 185.0°C)

2.3 Experimental Capabilities

a) Demonstration of relationship between the pressure and temperature of saturated steam in equilibrium with water

b) Demonstration of the vapour pressure curve 2.4 Overall Dimensions

Height : 1.15 m Width : 1.00 m Depth : 0.60 m

2.5 General Requirements

Electrical : 240VAC/1-phs/50Hz Water Supply : Distilled water


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3.0 INSTALLATION AND COMMISSIONING

3.1 Installation Requirements

The equipment should be installed on a firm, level work surface. A single phase

electrical supply will be required.

No other services are necessary.

3.2 Commissioning

1. Connect the mains input power supply plug to a nearest single-phase electrical supply of 230VAC/50Hz.

2. Push the reset button of the Earth Leakage Circuit Breaker (ELCB) inside the control panel after the main power supply is switched on. The ELCB should be kicked off, indicating that the ELCB is functioning properly. If not, have a trained wireman to inspect the equipment for any electrical leakage. The ELCB should be tested in a regular basis.

3. Open the valves at the feed port, V1, V2, & V3 and level sight tube. 4. Fill the boiler with distilled water through the feed port and make sure that the

water level is at about the half of the boiler’s height. Then, close the valves, V1 & V2 at the level sight tube.

5. Leave the vent valve, V3 at open position. 6. Turn on the power switch. All indicators on the front panel should lit-up. 7. Check the temperature and the pressure readings. The temperature reading

should be close to the surrounding temperature and the pressure reading should be 1 absolute bar.

8. Switch on the heater and observe the temperature in the boiler. The steam temperature rise as the water boils.

9. Allow steam to come out from the vent valve, V3 for about 30 seconds, and then close the valve. This step is important to remove air from the boiler as the accuracy of the experimental results will be significantly affected when air is present.

10. Then observe the pressure reading in the vessel. The pressure should rise when the temperature further increases.

11. Wait for sufficient time to heat up the water up to 10 bar and make sure that there is no leakage as the pressure increases. If any leakage is observed, fix it and repeat the above procedure.

12. Switch off the heater after the commissioning and allow the temperature to cool down.

13. Commissioning of the equipment is now complete.


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4.0 SUMMARY OF THEORY Marcet Boiler (Model: HE169) has been developed for investigating the relationship

between the pressure and temperature of saturated steam, in equilibrium with water, at all pressures between atmospheric and 10 bar (abs) (150 lb/in²).

Thermodynamics is a branch of physics, which deals with the energy, and work of a system. Thermodynamics deals only with the large-scale response of a system that we can observe and measure in experiments. Small-scale gas interactions are described by the kinetic theory of gasses, which is a compliment to thermodynamics.

An ideal gas can be characterized by three state variables: absolute pressure (P), volume (V), and absolute temperature (T). The relationship between them may be deduced from kinetic theory and is called the Ideal Gas law. The ideal gas law was originally determined empirically and is simply.

P V = n R T Where, P = Absolute pressure V = Volume n = Amount of substance (moles) R = Ideal gas constant T = Absolute temperature (K)

If a gas behaves exactly as the ideal gas laws would predict it to behave in terms of volume, pressure, moles, and temperature, then the gas is said to be an ideal gas. On the other hand, the gas deviates from Ideal Gas behavior, then the gas is said to be acting like a "real gas".

When energy increases within water, the increasing of activities among the molecules enables the increase in the number of molecule escape from the surface until an equilibrium state is reached. The state of equilibrium depends on the pressure between the water surface and steam. At lower pressure, the molecules become easier leaving the water surface while less energy required in achieving the state of equilibrium (boiling point). The temperature where equilibrium occurs at a given pressure level is called saturated temperature.

The measured value of the slope of the graph (dT/dP) SAT obtained from the practical results can be compared with corresponding values calculated from the data in steam tables. Clausius-Clapeyron states:

fg

fg

SAT h

Tv

dP

dT

gf

gf

SAT hh

vvT

dP

dT

)(


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And hf + hfg = hg Hence, hfg = hg - hf

fg

g

fg

gf

SAT h

Tv

h

vvT

dP

dT

)(

As vg >> vf in which, vf = specific volume of saturated liquid vg = specific volume of saturated vapor hf = enthalpy of saturated liquid hg = enthalpy of saturated vapor hfg = latent heat of vaporization


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5.0 GENERAL OPERATING PROCEDURES

5.1 General Start-up Procedures

1. Perform a quick inspection to ensure that the unit is in proper operating condition.

2. Connect the unit to the nearest power supply. 3. Check whether water is already filled in boiler. If already filled skip step 4 and

5 below. 4. Open the valves at the feed port and the level sight tube (V1, V2, & V3). 5. Fill the boiler with distilled water through the feed port and make sure that the

water level is at about the half of the boiler’s height. Then, close the valves, V1 & V2 at the level sight tube.

6. Turn on the power supply switch. 7. Now you are ready to carry on with the experiment.

5.2 General Shut-down Procedures

1. Switch off the heater and allow the boiler temperature to drop until room temperature. Note: Do not open the valve at the water inlet port as it is highly pressurized at high temperature.

2. When it has dropped to room temperature, switch off the main switch and the main power supply.

3. Retain the water next use. 4. To drain the water open the upper part of the level sight tube, V3 and then

open V1 and V2 to drain off the water.


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6.0 EXPERIMENTAL PROCEDURE 6.1 Experiment: The Fundamental Pressure-Temperature Relationship of

Saturated Steam in Equilibrium

Objectives: 1. To demonstrate the relationship between the pressure and temperature of

saturated steam in equilibrium 2. To demonstrate of the vapour pressure curve Procedures:

1. Perform the general start-up procedures as described in Section 5.1.

2. If the boiler is initially filled with water, open the valves at the level side tube

(V2 & V3) to check the water level. Pour in additional distilled water if

necessary. Then, close the valves.

3. Set the temperature controller to 185.0 °C which is slightly above the expected

boiling point of the water at 10.0 bar (abs).

4. Open the vent valve, V3 and turn on the heater.

Important:

Always make sure that the valves at the level sight tube are closed

before turning on the heater as the sight tube is not designed to

withstand high pressure and temperature.

5. Observe the steam temperature rise as the water boils.

6. Allow steam to come out from the valve, V3 for about 30 seconds, and then

close the valve. This step is important to remove air from the boiler as the

accuracy of the experimental results will be significantly affected when air is

present.

7. Record the steam temperature and pressure when the boiler is heated until the

steam pressure reaches 10.0 bar (abs). (Make the intervals of pressure data

for 0.1 initially, followed by 0.2 and 0.5 for the following data)

Warning!

Never open the valve when the boiler is heated as pressurized steam can

cause severe injury.

8. Then, turn off the heater and the steam temperature and pressure will begin to

drop. Start to record steam temperature when the boiler is cooled until the

steam pressure reaches atmospheric pressure.

9. Allow the boiler cool down to room temperature.

10. Record the steam temperatures at different pressure readings when the boiler

is heated and cooled.


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RESULTS:

1. Complete experimental data sheet.

2. Plot the graph of average temperature, T, against absolute pressure, P.

3. Plot the graph measured and calculated slope as a function of absolute

pressure.

4. Measure/calculate the slope of the graph using certain points of pressure and

average temperature. Report these values in result section.

Note:

fg

fg

SAT h

Tv

dP

dT

Plot SATdP

dT

versus P and

fg

fg

h

Tvversus P on a same graph.

Discussion:

1. Why is it necessary to remove air from the boiler at the beginning of the experiment?

2. Compare the graph plotted from measured data to that of the calculated data. 3. Discuss any discrepancy and sources of error of the experiment. 4. Discuss the liquid and vapor behavior observed through the experiment 5. Discuss 4 applications of boilers in industries. Elaborate you answer in detail.


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7.0 EQUIPMENT MAINTENANCE 1. Use only distilled water for the test to prolong the boiler’s life. 2. It is not necessary to drain the water from the boiler as there is no rusting

component in the boiler. In case of draining is necessary, incline the bench to a side and open the heater flange slowly. Be extremely careful when draining; never allow water to contact with the heater terminals.

3. Always check and rectify any leaks. 4. Always make sure that the boiler vessel is filled with sufficient water to cover the

heater element. Water level at half of the boiler’s height is sufficient to cover the heating element.

5. Restore the system to operating conditions after any repair job. Replace a new seal if necessary.

6. The unit requires no major maintenance. To prevent unnecessary damage to the unit, always consult the manufacturer for any maintenance or repair works. Maintenance and repair must be done by well trained technician. Consult the manufacturer for any replacement parts.

8.0 SAFETY AND PRECAUTIONS

1. The unit must be operated under the supervision of trained personnel. 2. All operating instructions supplied with the unit must be carefully read and

understood before attempting to operate the unit. 3. Do not open the valves on the level sight tube when the vessel is in operation. The

sight tube is not design to withstand high pressure and high temperature. 4. Always check and rectify any leaks. 5. Always make sure that the boiler vessel is filled with sufficient water to cover the

heater element. Water level at half of the boiler’s height is sufficient to cover the heating element.

6. Do not touch the hot components of the unit. Be extremely careful when handling liquid at high temperature.

9.0 REFERENCES

Yunus A. Cengal & Michael A. Boles, “Thermodynamics – An Engineering Approach”, 3rd Edition, 4th Edition, McGraw Hill, 2002.


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Appendix

Pressure, P (bar)

Temperature, T

Measured

Slope, dT/dP

Calculated

Slope, Tvg/hfg

Gauge Absolute Increase (0C)

Decrease (0C)

Average Tavc (0C)

Average Tavc (K)

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

1.10

1.20

1.30

1.40

1.50

1.60

1.70

1.80

1.90

2.00

2.50

3.00

3.50

4.00

4.50

5.00

5.50

6.00

6.50

7.00

7.50

8.00

8.5

9.00

marcet boiler manual

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